1. Field of the Invention
The present invention relates to a collision determining apparatus for a vehicle that determines a vehicle collision, and causes an occupant protection apparatus such as, for example, an airbag apparatus or a seatbelt pretensioner to be operated.
Priority is claimed on Japanese Patent Application No. 2004-277693, filed Sep. 24, 2004, Japanese Patent Application No. 2004-277694, filed Sep. 24, 2004, Japanese Patent Application No. 2004-277695, filed Sep. 24, 2004, and on Japanese Patent Application No. 2004-277696, filed Sep. 24, 2004, the contents of which are incorporated herein by reference.
2. Description of Related Art
Conventionally, collision determining apparatuses for vehicles are known that are provided with acceleration sensors that, for example, measure the acceleration (or the deceleration) that is applied to a vehicle. These apparatuses detect changes in the acceleration of a vehicle using acceleration signals that are output from the acceleration sensor, and perform temporal primary integration or temporal secondary integration on the acceleration signals. When these integral values exceed predetermined respective threshold values, an occupant protection apparatus such as, for example, an airbag apparatus or a seatbelt pretensioner is operated.
When it is determined by this type of collision determining apparatus for a vehicle that the vehicle is in a collision, the airbag apparatus, for example, ignites a gas generating agent inside an inflator using a squib so that gas is generated by the inflator. The airbag is then inflated by this gas so as to control any secondary collision between an occupant and components inside the vehicle interior (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2003-191817).
In a conventional collision determining apparatus for a vehicle such as that described above, it is necessary for the state of the collision to be determined in a short time from when the collision occurs, and for the operation of an occupant protection apparatus to then be controlled.
However, by simply operating an occupant protection apparatus using a constant characteristic when the integral value of the acceleration signals output from the acceleration sensor exceeds a predetermined threshold value, problems arise in that the occupant protection apparatus is operated even when the collision is not so serious as to require the occupant protection apparatus to be operated, and in that the operating characteristics of the occupant protection apparatus are not appropriate to the state of the collision, and thus it is not possible to ensure the desired protection capability.
Moreover, it is not possible to determine precisely the state of a collision simply by determining whether or not a correlation between the respective integral values from the primary integration and secondary integration of the acceleration signals (i.e., changes in the movement speed of the occupant and the amount of movement of the occupant) that are output from the acceleration sensor exceeds a predetermined threshold value. As a result, the problem arises in that an occupant protection apparatus may be operated at inappropriate times.